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Studying the Effects of Tumor-Secreted Paracrine Ligands on Macrophage Activation using Co-Culture with Permeable Membrane Supports
Published on: November 28, 2019
Innate-immune therapy for lung carcinoma based on tissue-macrophage activation with lipopolysaccharide
Mami Hino1, Chie Kohchi, Takashi Nishizawa
1Institute for Health Sciences, Tokushima Bunri University, Nishihama, Yamashiro-cho, Tokushima-shi, 770-8514, Japan.
Background:
Over the last decade, tumor-specific antigens have been discovered, but so far it has not been possible to use them as part of an effective acquired immunotherapy. This failure may be due to the fact that the expression of the MHC class 1 is low and in lung cancer cells is heterogeneous. Therefore, it may be advantageous to develop techniques that activate the antitumor mechanism of the innate immune system. An experimental model was developed for testing lung cancer therapies that are based on the stimulation of macrophages, which then activate innate immunity.
Materials And Methods:
A549, a human lung adenocarcinoma cell line, was co-cultured with a rat macrophage cell line (NR8383), or a human macrophage cell line (THP 1) at the ratios of 1:1 or 1:5. The experiments were performed with lipopolysaccharide (LPS) or in its absence. The cytotoxicity rate to A549 cells was estimated over time using a dye-uptake method and the amount of lactate dehydrogenase released was measured. The amount of nitric oxide (NO) induced in the medium was assayed, because it may be a candidate as a useful cytotoxic factor.
Results:
High cytotoxicity was observed to A549 cells when co-cultured with NR8383 cells in the presence of LPS. This effect was not observed in the absence of LPS. Similar results, although to a lesser extent, were observed when A549 cells were co-cultured with THP-1 cells. A high concentration of NO was measured in the co-culture medium of A549 cells and NR8383 cells when LPS was present.
Conclusion:
The induction of cell death in lung cancer cells occurred after contact with macrophages that had been activated by LPS. The NO that was produced by macrophages in response to LPS was responsible for some of this effect.
Insights
Activated macrophages, stimulated by lipopolysaccharide (LPS), effectively kill lung cancer cells. This innate immune response, mediated by nitric oxide (NO), offers a promising new avenue for lung cancer immunotherapy.
Area of Science:
- Immunology
- Cancer Research
- Cell Biology
Background:
- Acquired immunotherapies targeting tumor-specific antigens have shown limited success in lung cancer due to heterogeneous MHC class I expression.
- Activating the innate immune system presents a potential alternative strategy for lung cancer treatment.
- This study explores macrophage-based therapies to stimulate innate immunity against lung cancer.
Purpose of the Study:
- To investigate the efficacy of macrophage-mediated cytotoxicity against lung adenocarcinoma cells.
- To determine the role of lipopolysaccharide (LPS) in activating macrophages for cancer cell killing.
- To assess the contribution of nitric oxide (NO) to macrophage-induced tumor cell death.
Main Methods:
- Co-culture of A549 human lung adenocarcinoma cells with rat (NR8383) or human (THP-1) macrophage cell lines at varying ratios.
- Treatment with lipopolysaccharide (LPS) to stimulate macrophages.
- Assessment of A549 cell cytotoxicity using dye-uptake and lactate dehydrogenase release assays.
- Quantification of nitric oxide (NO) production in the co-culture medium.
Main Results:
- Co-culture with NR8383 macrophages significantly enhanced A549 cell cytotoxicity in the presence of LPS.
- THP-1 macrophages also demonstrated cytotoxic effects, though to a lesser extent than NR8383 cells.
- High concentrations of nitric oxide (NO) were detected in co-cultures stimulated with LPS, correlating with cytotoxicity.
Conclusions:
- LPS-activated macrophages induce cell death in lung cancer cells through direct contact.
- Nitric oxide (NO) produced by activated macrophages plays a significant role in mediating this anti-cancer effect.
- Macrophage-based innate immune activation represents a viable strategy for lung cancer therapy.
